A couple of options come to mind Scott ;
The most efficient , cleanest , costliest , is to take it to a large machine shop and have the tap spark eroded out. You may still have to retap and fit a helicoil .
Alternatively you could try to destroy the tap by pounding it with a punch , but this is high risk , and you will end up ruining the hole and have to redrill and retap for a larger bolt , or helicoil , also pricey.
Normally the HB is a drive fit on the crank , you should only need a little 620 loctite if it slips on easy .
